The pyrolysis of coal commonly produces a high density coal tar, more dense than water, which is difficult to process and refine to useful products. Hydrogenation of the coal tar has been attempted, however, currently there is no efficient process or apparatus for effecting hydrogenation of the coal tar into useful products.
Coal, which is plentifully available in this country contains a relatively high content of sulfur, typically up to about 5 weight percent and its pyrolysis produces coal tar and coke having objectionable quantities of sulfur impurities. The sulfur impurities in the coke product are extremely difficult to remove by conventional technology and the coke thus has a low value and limited utility.
During pyrolysis, coal also has a tendency to plasticize, becoming soft and agglomerating. This tendency makes the coal difficult to process and handle in most pyrolysis equipment and, accordingly, there is a need for equipment that can efficiently maintain coke in a friable state during its pyrolysis. In my prior patent, U.S. Pat. No. 3,284,915, I disclose an apparatus for calcining green pertroleum coke which has an internal oscillating solids baffle that prevents agglomeration of the coke. Although I suggested that this apparatus could also be used for coal calcination, there is no obvious application of this apparatus for the simultaneous desulfurization of coke and hydrogenation of the coal tar products.